In Moana, Maui the demigod and later a few Motunui sailor are shown tying this knot.
This knot is called Bowline Knot.
Bowline is an ancient and simple knot used to form a fixed loop at the end of a rope. It has the virtues of being both easy to tie and untie; most notably, it is easy to untie after being subjected to a load.
The bowline is commonly used in sailing small craft, for example to fasten a halyard to the head of a sail or to tie a jib sheet to a clew of a jib.
The knot they tie in Moana is often mistaken as a bowline, BUT it is actually called a Flying Bowline, also known as a Speed Bowline or a Tugboat Bowline.
It's a common knot used by sailors to throw a loop in the end of a rope. They do this to throw a loop to someone who has gone overboard or to throw a loop over a cleat or boring of a kind when tying something off.